RESUMO
Background: Catheter ablation failure poses a clinical challenge for epicardial or intramural ventricular arrhythmia (VA); however, guidewire ablation within the coronary venous system (CVS) may be effective and safe for targeting VAs. Methods: The ex vivo phase included four steps. In step 1, the steam pop incidence rates during guidewire ablation at power settings of 5, 10, 15, 20, and 25 W were analyzed using 10 mm- and 20 mm-tip guidewires. In step 2, guidewire ablation was performed for application durations of 10, 20, 30, 40, 50, 60, and 90 s, and the lesion size was measured. In step 3, the effects of saline infusion (0, 1, 2, 3, and 4 mL/min) on lesion dimensions and steam pop formation were examined. In step 4, an orthogonal array was constructed to obtain the optimal guidewire ablation parameters. In the in vivo phase, guidewire ablation within the CVS was performed in three dogs, and the lesion features in 10 days after ablation were observed. Results: In step 1, the steam pop incidence rates at 5, 10, 15, 20, and 25 W were 0%, 0%, 12.5%, 62.5%, and 100% using the 10 mm-tip guidewires and 0%, 0%, 0%, 25%, and 75% using the 20 mm-tip guidewires, respectively. In step 2, we found that the lesion areas increased with an increase in the ablation duration (the maximum lesion diameters at 30, 60, and 90 s were 4.9 ± 0.4, 7.0 ± 0.8, and 9.2 ± 0.7 mm in the 10 mm group and 3.2 ± 0.5, 4.5 ± 0.4, and 5.3 ± 0.7 mm in the 20 mm-tip group, respectively). In step 3, we observed that saline infusion was negatively correlated with ablation lesions but had a lower risk of steam pop. The optimal parameters for the 20 mm-tip guidewire ablation were 15 W, 50 s, and 2 mL/min or 20 W, 70 s, and 2 mL/min. In the in vivo phase, effective ablation lesions with maximum and minimum diameters of 3.2 ± 0.3 and 2.8 ± 0.5 mm, respectively, were created by the guidewires during the 10-day observation period after ablation. Conclusion: This novel radiofrequency guidewire ablation technique can feasibly create effective lesions within the CVS, which may improve the efficacy of catheter ablation for challenging epicardial or intramural VA.
RESUMO
BACKGROUND: A novel ablation technique with guidewire has emerged as a promising approach for mapping and ablation of arrhythmias originating from left ventricular summit. However, its biophysical characteristics have not been fully clarified. METHODS AND RESULTS: In the in vitro experiment, guidewire ablation (GA) was performed in vessel models of 1.17 and 2.24 mm to determine the maximum safety power. Then with the maximum safety power, the predictive value of generator impedance (GI) drop on lesion radius was explored. In the in vivo experiment, the feasibility of the maximum safety power and lesion formation was verified in the living swine. It was found that in both groups, the incidence of steam pops increased along with the raise of ablation power, and the maximum safety power was 10 W for the 1.17-mm group and 15 W for the 2.24-mm group. There was a strong linear correlation between GI drop and maximum lesion radius (in 1.17 mm-10-W group: r = .961; in 2.24 mm-15-W group: r = .918). In the in vivo experiment, besides ventricular fibrillation happened once, no other complications were observed, and lesions were found at both 48-h and 8-week groups. CONCLUSIONS: The safety power of GA should be adjusted according to the diameter of the vessel. Besides, the GI drop can predict the lesion radius during GA.
